/* Copyright (c) 2010, Carl Burch. License information is located in the
 * com.cburch.logisim.Main source code and at www.cburch.com/logisim/. */

package com.cburch.logisim.std.arith;

import java.awt.Color;
import java.awt.Graphics;

import com.cburch.logisim.data.Attribute;
import com.cburch.logisim.data.BitWidth;
import com.cburch.logisim.data.Bounds;
import com.cburch.logisim.data.Direction;
import com.cburch.logisim.data.Location;
import com.cburch.logisim.data.Value;
import com.cburch.logisim.instance.InstanceFactory;
import com.cburch.logisim.instance.InstancePainter;
import com.cburch.logisim.instance.InstanceState;
import com.cburch.logisim.instance.Port;
import com.cburch.logisim.instance.StdAttr;
import com.cburch.logisim.tools.key.BitWidthConfigurator;
import com.cburch.logisim.util.GraphicsUtil;
import static com.cburch.logisim.util.LocaleString.*;

public class Adder extends InstanceFactory {
    static final int PER_DELAY = 1;

    private static final int IN0   = 0;
    private static final int IN1   = 1;
    private static final int OUT   = 2;
    private static final int C_IN  = 3;
    private static final int C_OUT = 4;

    public Adder() {
        super("Adder", getFromLocale("adderComponent"));
        setAttributes(new Attribute[] {
                StdAttr.WIDTH
            }, new Object[] {
                BitWidth.create(8)
            });
        setKeyConfigurator(new BitWidthConfigurator(StdAttr.WIDTH));
        setOffsetBounds(Bounds.create(-40, -20, 40, 40));
        setIconName("adder.svg");

        Port[] ps = new Port[5];
        ps[IN0]   = new Port(-40, -10, Port.INPUT,  StdAttr.WIDTH);
        ps[IN1]   = new Port(-40,  10, Port.INPUT,  StdAttr.WIDTH);
        ps[OUT]   = new Port(  0,   0, Port.OUTPUT, StdAttr.WIDTH);
        ps[C_IN]  = new Port(-20, -20, Port.INPUT,  1);
        ps[C_OUT] = new Port(-20,  20, Port.INPUT,  1);
        ps[IN0].setToolTip(getFromLocale("adderInputTip"));
        ps[IN1].setToolTip(getFromLocale("adderInputTip"));
        ps[OUT].setToolTip(getFromLocale("adderOutputTip"));
        ps[C_IN].setToolTip(getFromLocale("adderCarryInTip"));
        ps[C_OUT].setToolTip(getFromLocale("adderCarryOutTip"));
        setPorts(ps);
    }

    @Override
    public void propagate(InstanceState state) {
        // get attributes
        BitWidth dataWidth = state.getAttributeValue(StdAttr.WIDTH);

        // compute outputs
        Value a = state.getPort(IN0);
        Value b = state.getPort(IN1);
        Value c_in = state.getPort(C_IN);
        Value[] outs = Adder.computeSum(dataWidth, a, b, c_in);

        // propagate them
        int delay = (dataWidth.getWidth() + 2) * PER_DELAY;
        state.setPort(OUT,   outs[0], delay);
        state.setPort(C_OUT, outs[1], delay);
    }

    @Override
    public void paintInstance(InstancePainter painter) {
        Graphics g = painter.getGraphics();
        painter.drawBounds();

        g.setColor(Color.GRAY);
        painter.drawPort(IN0);
        painter.drawPort(IN1);
        painter.drawPort(OUT);
        painter.drawPort(C_IN,  "c in",  Direction.NORTH);
        painter.drawPort(C_OUT, "c out", Direction.SOUTH);

        Location loc = painter.getLocation();
        int x = loc.getX();
        int y = loc.getY();
        GraphicsUtil.switchToWidth(g, 2);
        g.setColor(Color.BLACK);
        g.drawLine(x - 15, y, x - 5, y);
        g.drawLine(x - 10, y - 5, x - 10, y + 5);
        GraphicsUtil.switchToWidth(g, 1);
    }

    static Value[] computeSum(BitWidth width, Value a, Value b, Value c_in) {
        int w = width.getWidth();
        if (c_in == Value.UNKNOWN || c_in == Value.NIL) {
            c_in = Value.FALSE;
        }

        if (a.isFullyDefined() && b.isFullyDefined() && c_in.isFullyDefined()) {
            if (w >= 32) {
                long mask = (1L << w) - 1;
                long ax = a.toIntValue() & mask;
                long bx = b.toIntValue() & mask;
                long cx = c_in.toIntValue() & mask;
                long sum = ax + bx + cx;
                return new Value[] { Value.createKnown(width, (int) sum),
                    ((sum >> w) & 1) == 0 ? Value.FALSE : Value.TRUE };
            } else {
                int sum = a.toIntValue() + b.toIntValue() + c_in.toIntValue();
                return new Value[] { Value.createKnown(width, sum),
                    ((sum >> w) & 1) == 0 ? Value.FALSE : Value.TRUE };
            }
        } else {
            Value[] bits = new Value[w];
            Value carry = c_in;
            for (int i = 0; i < w; i++) {
                if (carry == Value.ERROR) {
                    bits[i] = Value.ERROR;
                } else if (carry == Value.UNKNOWN) {
                    bits[i] = Value.UNKNOWN;
                } else {
                    Value ab = a.get(i);
                    Value bb = b.get(i);
                    if (ab == Value.ERROR || bb == Value.ERROR) {
                        bits[i] = Value.ERROR;
                        carry = Value.ERROR;
                    } else if (ab == Value.UNKNOWN || bb == Value.UNKNOWN) {
                        bits[i] = Value.UNKNOWN;
                        carry = Value.UNKNOWN;
                    } else {
                        int sum = (ab == Value.TRUE ? 1 : 0)
                            + (bb == Value.TRUE ? 1 : 0)
                            + (carry == Value.TRUE ? 1 : 0);
                        bits[i] = (sum & 1) == 1 ? Value.TRUE : Value.FALSE;
                        carry = (sum >= 2) ? Value.TRUE : Value.FALSE;
                    }
                }
            }
            return new Value[] { Value.create(bits), carry };
        }
    }
}
